1. Field of the Invention
The present invention relates generally to electronic controls for vehicles, and more particularly, to an electronically controlled pedal with a hysteresis device.
2. Description of the Related Art
Vehicles, and in particular automotive vehicles, utilize a foot-operated device, such as a brake pedal or a throttle control pedal, also referred to as an accelerator pedal, to control the movement of the vehicle. Conventional brake systems include a brake pedal for transmitting a braking force from the vehicle operator to the wheels of the vehicle. Similarly, conventional throttle control systems include a throttle pedal to transmit a signal from the vehicle operator to a controller to control acceleration and movement of the vehicle. Recent innovations in electronics technology have led to increased use of electronic controls for vehicle systems, such as the throttle system or the brake system.
In an electronically controlled throttle control system, the pedal arm is attached to a position sensor, which senses the relative position of the pedal arm and transmits a signal to a controller to operate the throttle. The electronically controlled brake system operates in a similar manner. However, since the pedal arm is not attached to a mechanical device, such as a rod or cable, there is no resistance to depression of the pedal, and the pedal returns to a nominal position quicker than with a mechanical system. This resistance is referred to as hysteresis. Hysteresis is advantageous because it provides the driver with a better “feel” of the pedal. Without a predetermined amount of hysteresis in the pedal, the driver may experience increased foot fatigue from the rapid adjustment of the pedal, especially when driving over a long period of time. In the past, a mechanical device was utilized to simulate the resistance to depression produced by a brake rod or a throttle cable in conventional pedal system, and return the pedal to its resting position. For example, European Patent No. EP 0748713 A2 discloses the use of a spring to return the pedal to its resting position. Another example of a mechanical device is a friction pad connected to an extension of the pedal arm to develop hysteresis during depression of the pedal. However, previously known hysteresis devices are complicated and utilize many parts.
At the same time, various position sensing devices are known in the art to sense the relative position of the accelerator pedal as the operator depresses or releases the accelerator pedal in controlling movement of the vehicle. One example of a position sensing device is a potentiometer. Another example of a position sensing device is an induction sensor. While these types of sensors work well, they are relatively expensive and may be difficult to package within the confined interior environment of the vehicle.
Thus, there is a need in the art for a hysteresis device for use with an electronically controlled pedal that has a minimal number of component parts and is cost-efficient to produce.